Bunch-Hellemans, The advent of electricity

The Greeks and other ancient peoples knew that some substances attract others when one of them has been rubbed. Similarly, they must have encountered mild shocks. People still notice both today, as when clothing picks up lint without touching it or when a doorknob gives a slight shock on a dry winter’s day. Thales, often counted as the first scientist, investigated the attractive properties of rubbed amber in Ionia around 600 BCE. He compared it to magnetism and noted that it was similar, but different. More than 2000 years later, around 1570, the English scientist William Gilbert also studied magnetism and the corresponding attraction of rubbed amber and various rubbed jewels. He modified the Greek and Latin terms for amber to produce the English word electric as a noun describing a material that behaved like amber. Nearly a hundred years later, in 1650, the term electricity was coined to refer to the force itself.

In the same year that electricity entered English, a German scientist, Otto von Guericke, was working with a method he had developed for making more electricity than could be made by rubbing a small piece of amber. He worked with a different electric, sulfur. He formed this electric into a ball, so it could be rubbed continuously by rotating it. Von Guericke was the first to observe light produced by electricity. Similar experiments produced light from electricity in England.

The electricity produced by von Guericke faded away soon after the ball stopped rotating. Shocks and lights were evanescent experiences. About a hundred years after the use of rotating balls, however, scientists in Leyden (Leiden, the Netherlands) learned that electricity could be stored in water in glass jars and conducted in and out with metal wires or nails. Modern versions are somewhat different in construction, but the main impact of the Leiden jar was the same. A large charge could be stored up over time and then released by touching the conductor. Some terrific shocks resulted, and the jars became popular in parlors as well as with scientists.

Still, no one knew what electricity was. It was not even clear whether there was one type or two (different electrics attracted or repelled different light substances, although the shocks seemed to be the same). Accidentally, a scientist in Italy, Luigi Galvani, found that severed frogs’ legs twitched in response to electricity and that they also responded the same way when touching metal that was not charged. Another Italian, Alessandro Volta, who had been experimenting with electricity, found that the reaction was chemical. He built an apparatus, which came to be known as the voltaic pile, that offered the first method of producing electricity in any quantity without rubbing. Improvements on the voltaic pile are the familiar batteries of today.

The main difference between electricity stored in a Leiden jar and that released by a battery is that chemically produced electricity does not all rush out at once. Instead, a steady flow like the current of a river appears. For the first time, electricity became available for periods of time, instead of instants. Within 20 years, the next key event occurred, also by accident. Hans Christian Oersted discovered that the connection between electricity and magnetism, suspected since at least the time of Thales, was real. An electric current could produce magnetic effects. In another ten years the converse was shown, and magnets were being used to generate electric currents. With the development of powerful currents produced by magnetic generators, the stage was set for the use of electric power for light, for communication, and for production of motion.

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